Vertical fluxes of nitrate in the seasonal nitracline of the Atlantic sector of the Arctic Ocean

Source at http://dx.doi.org/10.1002/2016JC011779 This study compiles colocated oceanic observations of high-resolution vertical profiles of nitrate concentration and turbulent microstructure around the Svalbard shelf slope, covering both the permanently ice-free Fram Strait and the pack ice north of Svalbard. The authors present an overview over the seasonal evolution of the distribution of nitrate and its relation to upper ocean stratification. The average upward turbulent diffusive nitrate flux across the seasonal nitracline during the Arctic summer season is derived, with average values of 0.3 and 0.7 mmol m−2 d−1 for stations with and without ice cover, respectively. The increase under ice-free conditions is attributed to different patterns of stratification under sea ice versus open water. The nitrate flux obtained from microstructure measurements lacked a seasonal signal. However, bottle incubations indicate that August nitrate uptake was reduced by more than an order of magnitude relative to the May values. It remains inconclusive whether the new production was limited by an unidentified factor other than NO3− supply in late summer, or the uptake was underestimated by the incubation method.</p

Fat balance and ageing : results from the Québec family study

The aim of the present study was to evaluate changes in participation in physical activity and in fat and alcohol intake associated with ageing. This issue was examined in adults (n 207) who were tested between 1978 and 1982 and re-tested 12 years later. These adults were 42.3 (sd 4.9) years of age at baseline. Their children (n 122) were tested over the same follow-up period. They were, on average, 12.5 (sd 1.9) years at entry into the study. A decrease in the proportion of daily energy intake as fat and an increase in participation in vigorous physical activities were observed over the 12-year period in both groups. The proportion of dietary energy as alcohol remained stable in adults whereas it increased markedly in children. Correlation analyses between baseline and follow-up levels were significant for dietary fat and alcohol intake in adults. In children, the levels of these variables in the growing years did not predict the levels attained 12 years later. Even though the adults displayed changes in fat balance generally following current public health recommendations, a substantial increase in skinfold thicknesses was observed in these subjects during follow-up. This observation suggests that there is a strong effect of age-related factors on fat balance

Peut-on utiliser des algues marines pour améliorer la qualité de l'eau des bassins d'exposition du Biodôme de Montréal?

Affiche présentée dans le cadre du Colloque de l'ARC, «La relève scientifique et la recherche collégiale : pratiques inspirantes au regard des chercheuses et chercheurs, et enjeux spécifiques à la formation des étudiantes et étudiants», dans le cadre du 84e Congrès de l'Acfas, Université du Québec à Montréal, Montréal, le 10 mai 2016.Dans les bassins d’eau recyclée du Biodôme de Montréal, le contrôle de l’azote et du phosphore dissous est essentiel, car leur accumulation peut dégrader la qualité de l’eau et devenir une source de stress pour les organismes aquatiques. Or, certaines algues marines ont la capacité d’absorber ces polluants tout en produisant de l’oxygène. L’objectif de notre  projet mené à l’École des pêches et de l’aquaculture du Québec était de développer un prototype de filtre biologique à base d’algues cultivées, efficace en termes d’absorption et de séquestration du nitrate et du phosphate dissous. Pour ce faire, les performances de deux espèces d’algues marines du golfe du Saint-Laurent, Palmaria palmata et Ulva lactuca, ont été évaluées dans des conditions similaires à celles des bassins du Biodôme de Montréal, soit deux températures (5 °C et 10 °C) et trois combinaisons de nutriments N-NO3- : P-PO43- (40:6, 50:7,5, 60:9 mg/L). Les résultats indiquent qu’aux densités testées (7 et 3 g AF/L; AF = algues fraîches), au bout de six jours, 10,2 ± 1,5 % du nitrate et 13,83 ± 9,0 % du phosphate présents dans l’eau ont été enlevés par P. palmata tandis que U. lactuca a enlevé 12,7 ± 3,3 % du nitrate et 13,01 ± 9,8 % du phosphate. La vitesse moyenne d’absorption journalière de l’azote par P. palmata était de 0,12 mg N/g AF  vs 0,34 mg N/g AF pour U. lactuca. Si les deux espèces montrent une bonne capacité d’épuration de l’eau, c’est U. lactuca qui absorbe l’azote le plus efficacement

Draft Genome Sequence of a Necrotoxigenic Escherichia coli Isolate

Here, we present the draft genome sequence of a necrotoxigenic Escherichia coli strain isolated from a patient following a very rapidly evolving, lethal necrotizing fasciitis

Arctic Ocean Microbial Community Structure before and after the 2007 Record Sea Ice Minimum

Increasing global temperatures are having a profound impact in the Arctic, including the dramatic loss of multiyear sea ice in 2007 that has continued to the present. The majority of life in the Arctic is microbial and the consequences of climate-mediated changes on microbial marine food webs, which are responsible for biogeochemical cycling and support higher trophic levels, are unknown. We examined microbial communities over time by using high-throughput sequencing of microbial DNA collected between 2003 and 2010 from the subsurface chlorophyll maximum (SCM) layer of the Beaufort Sea (Canadian Arctic). We found that overall this layer has freshened and concentrations of nitrate, the limiting nutrient for photosynthetic production in Arctic seas, have decreased. We compared microbial communities from before and after the record September 2007 sea ice minimum and detected significant differences in communities from all three domains of life. In particular, there were significant changes in species composition of Eukarya, with ciliates becoming more common and heterotrophic marine stramenopiles (MASTs) accounting for a smaller proportion of sequences retrieved after 2007. Within the Archaea, Marine Group I Thaumarchaeota, which earlier represented up to 60% of the Archaea sequences in this layer, have declined to <10%. Bacterial communities overall were less diverse after 2007, with a significant decrease of the Bacteroidetes. These significant shifts suggest that the microbial food webs are sensitive to physical oceanographic changes such as those occurring in the Canadian Arctic over the past decade

Description and Spatial Modelling of Benthic Communities Distribution in the Canadian Arctic Archipelago

In the Arctic, sea ice loss has already transformed the dominant sources and periodicity of primary production in some areas, raising concerns over climate change impacts on benthic communities. Considered to be excellent indicators of environmental changes, benthic invertebrates play important roles in nutrient cycling, sediment oxygenation and decomposition. However, this biological component of the Canadian Arctic Archipelago (CAA) is still somewhat poorly studied compared to other Arctic regions. To partly fill this need, this study aims to evaluate benthic community composition and its relationship to significant environmental drivers and to develop spatial predictive explanatory models of these communities to expand coverage between sampled stations across the Kitikmeot Sea region and Parry Channel. Results from previously collected samples suggest that biodiversity is higher in this region compared to the Beaufort and Baffin Seas, two adjacent regions to the West and East, respectively. This finding leads to the main hypothesis that (1) benthic communities are succeeding one another, forming an ecotone (transition area) between the Beaufort Sea and the Baffin Sea. Other hypotheses are that (2) Pacific Ocean water influence through the CAA can explain part of this gradient, and that (3) terrigenous inputs affect the distribution of species. Overall, results tend to confirm hypotheses. Generalized Linear Models (GLMs) (with R2 up to 0.80) clearly displayed a succession in community distribution from Queen-Maud Gulf (Southwest) to Lancaster Sound (Northeast). Such models can be useful in identifying potential biodiversity hotspots and as a baseline for marine spatial planning purposes. Further, Pacific origin water (traced with concentrations of nitrate relative to phosphate) and terrigenous inputs (traced with silicate concentrations) were related to species and community distribution. Given that these two inputs/factors are generally increasing in the Canadian Arctic, their influence on benthic communities may also be seen to increase in the upcoming years

Correlates of coronary artery calcification prevalence and severity in patients with heterozygous familial hypercholesterolemia

Background Determinants of coronary artery calcification (CAC) prevalence and severity in heterozygous familial hypercholesterolemia (HeFH) remain understudied. The objective of this cross-sectional study was to investigate correlates of CAC in patients with HeFH. Methods A CAC score was calculated by a noncontrast computed tomography scan in women (n = 68) and men (n = 78) with genetically defined HeFH. We classified CAC prevalence and severity using 3 categories: CAC score = 0 Agatston Unit (AU), CAC score = 1-100 AU, and CAC score > 100 AU. Information on potential correlates of CAC including familial and personal health history, cardiovascular risk factors, lipid-lowering medication, and lifestyle habits was collected. Results A total of 95 patients had prevalent CAC. Independent correlates of CAC prevalence and severity included age (odds ratio [OR] per 10 years: 5.06, 95% confidence interval [CI]: 3.19, 7.93, P < 0.0001), family history of premature cardiovascular disease (OR: 3.88, 95% CI: 1.71, 8.81, P = 0.001), male sex (OR: 3.40, 95% CI: 1.49, 7.78, P = 0.004), statin use (OR: 15.5, 95% CI: 1.89, 126, P = 0.01), diet quality assessed with the Alternative Healthy Eating Index score (OR per 1 standard deviation: 0.59, 95% CI: 0.39, 0.90, P = 0.01), ever smoking (OR: 3.06, 95% CI: 1.20, 7.81, P = 0.02), receptor-negative genotype (OR: 3.17, 95% CI: 1.16, 8.66, P = 0.02), lipoprotein(a) year-score (OR per 1 standard deviation of log-transformed year-score: 1.53, 95% CI: 0.99, 2.36, P = 0.05). Conclusions In individuals with HeFH, age, family history of premature cardiovascular disease, sex, statin use, diet quality, smoking status, the LDLR genotype, and lipoprotein(a) concentrations were independently associated with CAC prevalence and severity.Contexte Les déterminants de la prévalence et de la sévérité de la calcification des artères coronaires (CAC) dans l'hypercholestérolémie familiale hétérozygote (HFHe) demeurent peu étudiés. L’objectif de cette étude transversale était d'identifier les corrélats de la CAC chez des patients atteints d’HFHe. Méthodologie Un score calcique coronarien (SCC) a été calculé par un examen de tomodensitométrie sans contraste chez des femmes (n = 68) et des hommes (n = 78) avec HFHe génétiquement définie. Nous avons classé la prévalence et la gravité de la CAC en trois catégories : SCC = 0 unité d’Agatston (UA), SCC = 1 à 100 UA et SCC > 100 UA. Des renseignements ont été recueillis sur des corrélats potentiels de la CAC, dont les antécédents médicaux familiaux et personnels, les facteurs de risque cardiovasculaire, les médicaments hypolipidémiants et les habitudes de vie. Résultats Au total, 95 patients présentaient une CAC. Les corrélats indépendants de la prévalence et de la gravité de la CAC comprenaient l’âge (rapport de cotes [RC] par tranche de 10 ans : 5,06; intervalle de confiance [IC] à 95 % : 3,19 à 7,93; p < 0,0001), des antécédents familiaux de maladie cardiovasculaire précoce (RC : 3,88; IC à 95 % : 1,71 à 8,81; p = 0,001), le sexe masculin (RC : 3,40; IC à 95 % : 1,49 à 7,78; p = 0,004), l’emploi de statines (RC : 15,5; IC à 95 % : 1,89 à 126; p = 0,01), la qualité du régime alimentaire évaluée selon le score AHEI (Alternative Healthy Eating Index) (RC par écart-type : 0,59; IC à 95 % : 0,39 à 0,90; p = 0,01), le tabagisme (RC : 3,06; IC à 95 % : 1,20 à 7,81; p = 0,02), le génotype récepteur-négatif (RC : 3,17; IC à 95 % : 1,16 à 8,66; p = 0,02) et le score lipoprotéine(a)-année (RC par écart-type du score-année transformé en logarithme : 1,53; IC à 95 % : 0,99 à 2,36; p = 0,05). Conclusions Chez les personnes atteintes d’HFHe, l’âge, les antécédents familiaux de maladie cardiovasculaire précoce, le sexe, l’emploi de statines, la qualité du régime alimentaire, le statut de tabagisme, le génotype du LDLR et les concentrations de lipoprotéine(a) ont été associés de façon indépendante à la prévalence et à la gravité de la CAC

Contrasting effects of acidification and warming on dimethylsulfide 2 concentrations during a temperate estuarine fall bloom mesocosm 3 experiment

The effects of ocean acidification and warming on the concentrations of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) were investigated during a mesocosm experiment in the Lower St. Lawrence Estuary (LSLE) in the fall of 2014. Twelve mesocosms covering a range of pHT (pH on the total hydrogen ion concentration scale) from 8.0 to 7.2, corresponding to a range of CO2 partial pressures (pCO2) from 440 to 2900 μatm, at two temperatures (in situ and C5 °C; 10 and 15 °C) were monitored during 13 days. All mesocosms were characterized by the rapid development of a diatom bloom dominated by Skeletonema costatum, followed by its decline upon the exhaustion of nitrate and silicic acid. Neither the acidification nor the warming resulted in a significant impact on the abundance of bacteria over the experiment. However, warming the water by 5 °C resulted in a significant increase in the average bacterial production (BP) in all 15 °C mesocosms as compared to 10 °C, with no detectable effect of pCO2 on BP. Variations in total DMSP (DMSPt DparticulateCdissolved DMSP) concentrations tracked the development of the bloom, although the rise in DMSPt persisted for a few days after the peaks in chlorophyll a. Average concentrations of DMSPt were not affected by acidification or warming. Initially low concentrations of DMS (< 1 nmol L-1) increased to reach peak values ranging from 30 to 130 nmol L-1 towards the end of the experiment. Increasing the pCO2 reduced the averaged DMS concentrations by 66%and 69%at 10 and 15 °C, respectively, over the duration of the experiment. On the other hand, a 5 °C warming increased DMS concentrations by an average of 240% as compared to in situ temperature, resulting in a positive offset of the adverse pCO2 impact. Significant positive correlations found between bacterial production and concentrations of DMS throughout our experiment point towards temperatureassociated enhancement of bacterial DMSP metabolism as a likely driver of the mitigating effect of warming on the negative impact of acidification on the net production of DMS in the LSLE and potentially the global ocean.Fil: Benard, Robin. Laval University; CanadáFil: Ferreyra, Gustavo Adolfo. Laval University; CanadáFil: Michael, Scarratt. Maurice Lamontagne Institute, Fisheries And Oceans; CanadáFil: Sonia, Michaud. Maurice Lamontagne Institute, Fisheries And Oceans ; CanadáFil: Michel, Starr. Maurice Lamontagne Institute, Fisheries And Oceans; CanadáFil: Alfonso, Mucci. Université Mcgill; CanadáFil: Ferreyra, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Gosselin, Michel. Institut Des Sciences de la Mer de Rimouski; CanadáFil: Tremblay, Jean-Éric. Laval University; CanadáFil: Lizotte, Martine. Laval University; CanadáFil: Yang, Gui Peng. Ocean University; Chin

A food web model for the Baffin Bay coastal and shelf ecosystem. Part 1 : Ecopath Technical Report

This work was undertaken as part of a multidisciplinary research project funded by the Marine Observation Prediction and Assessment Network - MEOPAR (at ULaval), Canadian Institute of Health Research – CIHR (at University of Ottawa), and Sentinel North (at ULaval), and hosted at Université Laval, in Canada. The objective of the overall project is to support the food security (i.e., the availability and access to sufficient, safe, nutritious food that meets dietary preference) of Inuit communities of the Eastern Canadian Arctic, as well as to explore ways to adapt to effects of climate change. Inuit fish and hunt local marine species, from invertebrates to fish and marine mammals, which make a large part of their diet and are central to their food security. With temperatures increasing twice as fast as the global average and sea ice becoming thinner and forming later, climate change effects on the distribution and abundance of Arctic marine species are already taking place. To better understand the effects of climate change in important subsistence species, a multi-species model (Ecopath with Ecosim) will be used to inform the development of an integrated ecosystem assessment. The model will be used as a tool to co-create scenarios of ecosystem change with the community of Qikiqtarjuaq, Nunavut, to inform adaptation strategies regarding food security (e.g., potential of new fisheries in the region). This report describes the development of an Ecopath model of the Baffin Bay coastal and shelf ecosystem. The methodology, data used to construct the model, data gaps and limitations are described